Short Communication Use of propyl paraben to control growth and ochratoxin A production by Aspergillus section Nigri species on peanut meal extract agar Carla Barberis a,b , Andrea Astoreca a,b , Guillermina Fernandez-Juri a,b , Sofía Chulze a,c , Ana Dalcero a,c , Carina Magnoli a,c, ⁎ a Departamento de Microbiología e Inmunología, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional No. 36 Km 601 (5800) Río Cuarto, Córdoba, Argentina b Fellowship of CONICET, Argentina c Member of the Research Career of CONICET, Argentina abstract article info Article history: Received 16 June 2009 Accepted 16 August 2009 Keywords: Aspergillus section Nigri Propyl paraben Growth parameters Ochratoxin A This study was carried out to determine the efficacy of the phenolic antioxidant propyl paraben (PP) under different interacting water activity (a W ) and temperature regimes on lag phase, growth rate and Ochratoxin A production by Aspergillus section Nigri strains. In this experiment six Aspergillus section Nigri strains were used. Peanut meal extract agar (PMEA) was prepared at 2%. The a W of the medium was adjusted to 0.995, 0.980 and 0.930, PP levels of 1, 5, 10 and 20 mmol/L were added to the basic medium. Plates were inoculated and incubated for 30 days at 18 and 25 °C. Lag phase (h) and radial growth rates (mm/day) were calculated. In control treatments, the lag phase increased and the growth rate decreased as a W reduced in all assayed strains. At all a W levels, when antioxidant concentrations increased the growth rate decreased. At 5, 10 and 20 mmol/L of PP the strains were not able to reach the exponential phase and completely inhibited fungal growth and OTA production regardless of a W used in all the evaluated strains. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Ochratoxin A (OTA) is the second mycotoxin, followed by aflatoxins, of significance in peanuts and peanut based products (Speijers and Speijers, 2004). In the last decade, OTA is receiving increased attention worldwide because of the hazard it poses to human and animal health (Mantle, 2002). This toxin has been considered in 2B group by the International Agency for Research on Cancer to be a potential carcinogen for human (International Agency for Research on Cancer, 1993). Peanut (Arachis hypogaea L.) is an economically important seed in Argentina. Most of the production is exported to different regions of the world, including European Union countries, and the USA; the rest is consumed internally. This oilseed is used for human consumption, mainly as peanut confectionery, peanut butter, oil production and as raw materials for feedstuffs (Secretaría de Agricultura, Ganadería, Pesca y Alimentación, 2007). Ochratoxigenic species belonging to Aspergillus niger aggregate and Aspergillus carbonarius are fungi most frequently associated with agricultural commodities. Furthermore, OTA has been detected in these products (Jimenez et al., 1991; Ismail, 2000; Magnoli et al., 2006, 2007). One strategy to reduce the entry of mycotoxins into the peanut chain is the use of chemical treatments during the storage stage of peanuts to reduce fungal growth and toxin production. From a human health perspective, the use of antioxidants such as butylatedhydrox- yanisole (BHA), propyl paraben (PP) and butylatedhydroxytoluene (BHT) as antimicrobial agents are allowed by the US Food and Drug Administration (FDA) and are regarded as safe (GRAS) chemicals. In addition, several studies revealed that different phenolic antioxidants as BHT, BHA and propyl gallate (THB) had beneficial effects on human and animal health (Codex Alimentarius, 2006). The last studies have shown that these antioxidants have a protective action in food since they could maintain organoleptic properties (Valle Vega and Florentino, 2000; Passone et al., 2005). Marín et al. (1995, 1999) showed that water activity (a W ) interaction is an important factor that influences on growth parameters and mycotoxin production when different fungal species grow in the presence of antioxidants. Several works have demonstrated that the food grade antioxidants BHA and PP control both growth and mycotoxin production by Fu- sarium and Aspergillus section Flavi species (Etcheverry et al., 2002; Reynoso et al., 2002; Torres et al., 2003; Nesci et al., 2003; Farnochi et al., 2005; Passone et al., 2005, 2007). In a previous study, the effect of BHA on growth rate and OTA production by Aspergillus section Nigri species on peanut meal-based media was evaluated (Barberis et al., International Journal of Food Microbiology 136 (2009) 133–136 ⁎ Corresponding author. Departamento de Microbiología e Inmunología, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional No. 36 Km 601 (5800) Río Cuarto, Córdoba, Argentina. Tel.: +54 358 4676429; fax: +54 358 4676231. E-mail address: cmagnoli@exa.unrc.edu.ar (C. Magnoli). 0168-1605/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.ijfoodmicro.2009.08.025 Contents lists available at ScienceDirect International Journal of Food Microbiology journal homepage: www.elsevier.com/locate/ijfoodmicro